TANDY/RADIO SHACK
=================

   4820ST/T (250-5140)

   Processor      80486SX/80487SX/ODP486/ODPR486/80486DX/80486DX2 
   Processor      20/25/33/40/50(internal)/50/66(internal)MHz     
   Speed          
   Chip Set       Unidentified                                    
   Video Chip Set None                                            
   Maximum        64MB                                            
   Onboard Memory 
   Maximum Video  None                                            
   Memory         
   Cache          None                                            
   BIOS           Unidentified                                    
   Dimensions     330mm x 218mm                                   
   I/O Options    Floppy drive interface, IDE interface, parallel 
                  port, PS/2 mouse port, serial ports (2)         
   NPU Options    80487SX                                         

<gopher://bitreich.org/I/th99/m/S-T/33812-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   | Purpose           | Location | Purpose          | Location |
   |-------------------+----------+------------------+----------|
   | PS/2 mouse port   |   CN1    | IDE interface    |   CN6    |
   |-------------------+----------+------------------+----------|
   | Serial port 1     |   CN2    | Power indicator  |    J1    |
   |-------------------+----------+------------------+----------|
   | Serial port 2     |   CN3    | IDE interface    |    J2    |
   |                   |          | LED              |          |
   |-------------------+----------+------------------+----------|
   | Parallel port     |   CN4    | External battery |    J3    |
   |-------------------+----------+------------------+----------|
   | Floppy drive      |   CN5    | Front panel      |    J4    |
   | interface         |          | connector        |          |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |              Function               | Label |   Position   |
   |-------------------------------------+-------+--------------|
   |>> | CMOS memory normal operation    |  JP1  |     Open     |
   |---+---------------------------------+-------+--------------|
   |   | CMOS memory clear               |  JP1  |    Closed    |
   |---+---------------------------------+-------+--------------|
   |>> | Monitor type select color       | SW1/3 |      On      |
   |---+---------------------------------+-------+--------------|
   |   | Monitor type select monochrome  | SW1/3 |     Off      |
   |---+---------------------------------+-------+--------------|
   |>> | Factory configured - do not     | SW1/4 | Unidentified |
   |   | alter                           |       |              |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   | Size |   Bank 0    |   Bank 1    |   Bank 2   |   Bank 3   |
   |------+-------------+-------------+------------+------------|
   | 1MB  | (4) 256K x  |    None     |    None    |    None    |
   |      |      9      |             |            |            |
   |------+-------------+-------------+------------+------------|
   | 2MB  | (4) 256K x  | (4) 256K x  |    None    |    None    |
   |      |      9      |      9      |            |            |
   |------+-------------+-------------+------------+------------|
   | 3MB  | (4) 256K x  | (4) 256K x  | (4) 256K x |    None    |
   |      |      9      |      9      |     9      |            |
   |------+-------------+-------------+------------+------------|
   | 4MB  | (4) 256K x  | (4) 256K x  | (4) 256K x | (4) 256K x |
   |      |      9      |      9      |     9      |     9      |
   |------+-------------+-------------+------------+------------|
   | 4MB  | (4) 1M x 9  |    None     |    None    |    None    |
   |------+-------------+-------------+------------+------------|
   | 5MB  | (4) 256K x  | (4) 1M x 9  |    None    |    None    |
   |      |      9      |             |            |            |
   |------+-------------+-------------+------------+------------|
   | 6MB  | (4) 256K x  | (4) 256K x  | (4) 1M x 9 |    None    |
   |      |      9      |      9      |            |            |
   |------+-------------+-------------+------------+------------|
   | 8MB  | (4) 1M x 9  | (4) 1M x 9  |    None    |    None    |
   |------+-------------+-------------+------------+------------|
   | 9MB  | (4) 1M x 9  | (4) 1M x 9  | (4) 256K x |    None    |
   |      |             |             |     9      |            |
   |------+-------------+-------------+------------+------------|
   | 10MB | (4) 256K x  | (4) 256K x  | (4) 1M x 9 | (4) 1M x 9 |
   |      |      9      |      9      |            |            |
   |------+-------------+-------------+------------+------------|
   | 12MB | (4) 1M x 9  | (4) 1M x 9  | (4) 1M x 9 |    None    |
   |------+-------------+-------------+------------+------------|
   | 16MB | (4) 1M x 9  | (4) 1M x 9  | (4) 1M x 9 | (4) 1M x 9 |
   |------+-------------+-------------+------------+------------|
   | 16MB | (4) 4M x 9  |    None     |    None    |    None    |
   |------+-------------+-------------+------------+------------|
   | 17MB | (4) 256K x  | (4) 4M x 9  |    None    |    None    |
   |      |      9      |             |            |            |
   |------+-------------+-------------+------------+------------|
   | 18MB | (4) 256K x  | (4) 256K x  | (4) 4M x 9 |    None    |
   |      |      9      |      9      |            |            |
   |------+-------------+-------------+------------+------------|
   | 20MB | (4) 1M x 9  | (4) 4M x 9  |    None    |    None    |
   |------+-------------+-------------+------------+------------|
   | 24MB | (4) 1M x 9  | (4) 1M x 9  | (4) 4M x 9 |    None    |
   |------+-------------+-------------+------------+------------|
   | 32MB | (4) 4M x 9  | (4) 4M x 9  |    None    |    None    |
   |------+-------------+-------------+------------+------------|
   | 33MB | (4) 4M x 9  | (4) 4M x 9  | (4) 256K x |    None    |
   |      |             |             |     9      |            |
   |------+-------------+-------------+------------+------------|
   | 34MB | (4) 256K x  | (4) 256K x  | (4) 4M x 9 | (4) 4M x 9 |
   |      |      9      |      9      |            |            |
   |------+-------------+-------------+------------+------------|
   | 36MB | (4) 4M x 9  | (4) 4M x 9  | (4) 1M x 9 |    None    |
   |------+-------------+-------------+------------+------------|
   | 40MB | (4) 1M x 9  | (4) 1M x 9  | (4) 4M x 9 | (4) 4M x 9 |
   |------+-------------+-------------+------------+------------|
   | 48MB | (4) 4M x 9  | (4) 4M x 9  | (4) 4M x 9 |    None    |
   |------+-------------+-------------+------------+------------|
   | 64MB | (4) 4M x 9  | (4) 4M x 9  | (4) 4M x 9 | (4) 4M x 9 |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     CPU TYPE SELECTION                     |
   |------------------------------------------------------------|
   |     Type      |    Socket     |    SW1/1     |    SW1/2    |
   |---------------+---------------+--------------+-------------|
   |    80486SX    |      CPU      |     Off      |     Off     |
   |---------------+---------------+--------------+-------------|
   |    ODP486     |      CPU      |      On      |     On      |
   |---------------+---------------+--------------+-------------|
   |    ODP486     |      NPU      |     Off      |     Off     |
   |---------------+---------------+--------------+-------------|
   |    ODPR486    |      CPU      |      On      |     Off     |
   |---------------+---------------+--------------+-------------|
   |    80487SX    |      CPU      |      On      |     On      |
   |---------------+---------------+--------------+-------------|
   |    80487SX    |      NPU      |     Off      |     Off     |
   |---------------+---------------+--------------+-------------|
   |    80486DX    |      CPU      |      On      |     Off     |
   |---------------+---------------+--------------+-------------|
   |   80486DX2    |      CPU      |      On      |     Off     |
   +------------------------------------------------------------+